diff --git a/Lib/pathlib.py b/Lib/pathlib.py
index 9f5e27b91178e6..af332e9f105b13 100644
--- a/Lib/pathlib.py
+++ b/Lib/pathlib.py
@@ -329,7 +329,13 @@ def _resolve(path, rest):
                     # parent dir
                     path, _, _ = path.rpartition(sep)
                     continue
-                newpath = path + sep + name
+
+                if path.endswith(sep):
+                    # special case for "/" root directory
+                    newpath = path + name
+                else:
+                    newpath = path + sep + name
+
                 if newpath in seen:
                     # Already seen this path
                     path = seen[newpath]
diff --git a/Lib/test/test_pathlib.py b/Lib/test/test_pathlib.py
index 04f7c3d86671bf..904626c38f028a 100644
--- a/Lib/test/test_pathlib.py
+++ b/Lib/test/test_pathlib.py
@@ -2385,6 +2385,19 @@ def test_resolve_loop(self):
         # Non-strict
         self._check_symlink_loop(BASE, 'linkW', 'foo', strict=False)
 
+    def test_resolve_pwd_root(self):
+        P = self.cls
+
+        # Resolve relative path in root directory.
+        old_path = os.getcwd()
+        os.chdir("/")
+        try:
+            given = P("var").resolve()
+            expect = P("/var")
+            self.assertEqual(given, expect)
+        finally:
+            os.chdir(old_path)
+
     def test_glob(self):
         P = self.cls
         p = P(BASE)